This invention relates to weighing apparatus employing load cells a a transducer element and more particularly to a low profile weighing apparatus employing a load cell of planar form resistant to torsional forces produced by off-center loading.
Many weighing scales now in use employ moment insensitive load cells. One commonly used is the dual beam load cell which includes a pair of parallel beams connected together at each end and having strain gages mounted on each beam. The dual beam load cell provides good resistance to off-center loading and can be compensated to improve performance in that respect. Disadvantages are its high profile, expensive machining and the labor involved in providing strain gages on more than one surface.
The use of single beam load cells has usually required expensive flexures and overload stops which make the structure expensive to machine and result in a high profile scale. The single beam load cell has not been used extensively without flexures because of the large compliance or lack of resistance to torsion in the transverse direction and, to a slightly lesser extent, in the longitudinal direction. Single beam load cells have usually been employed with strain gages aligned on the central longitudinal axis of the beam.